The invention relates to a process for the production of a nanoemulsion of less than 200 nm sized oil particles of a triglyceride or fatty acid ester in an aqueous phase by means of a high-pressure homogenizer.
Such a nanoemulsion can be characterized as a colloid-highly disperse two-phase system, and it can be clearly distinguished, based on laser light scattering measurements and electron microscope images, from associations (micelles) and solubilized products (micellar solutions=swollen micelles), as they are described, for example, in P. H. List, B. W. Muller and E. Nurnberg, "Emulsionen" [Emulsions], in "Arzneiformenlehre" [Manual of Pharmaceuticals] 1982, Wissenschaftliche Verlagsgesellschaft mbH [publishers], Stuttgart, pages 141-176. The nanoemulsion is defined with respect to coarsely disperse systems by a particle size of less than 200 nm.
So-called "microemulsions" have been disclosed in H. Sucker, P. Fuchs and P. Speiser, "Dermatica", in "Pharmazeutische Technologie" [Practice of Pharmacy] 1978, Georg Thieme publishers, Stuttgart, pages 663-665. Since the meaning of the term "microemulsion", however, has thus far not as yet been exactly clarified, the term nanoemulsion is employed herein for denoting an emulsion with less than 200 nm sized oil particles.
In the conventional preparation of "microemulsions", highly concentrated tenside-cotenside mixtures are needed in order to effect minimum surface tension and to ensure physical stability of the emulsion. The most troublesome drawbacks from the viewpoint of pharmaceuticals are the high tenside-cotenside concentrations necessary for preparation, and the toxicity of the known emulsifier complexes. Due to the aforementioned disadvantages, practical use of the "microemulsions", for example as medicine vehicles for lipophilic active agents, or their usage for parenteral alimentation could not be considered heretofore.